Transition noise analysis of thin film magnetic recording media

A simple but accurate expression for general non-stationary noise correlation in the presence of a recorded transition is analyzed in terms of both noise voltage and spectral measurements. The parameters of this analysis are solely the cross track correlation width s, the transition shape and parameter a, the head-medium spacing d, and the replay gap length g. It is shown that although the noise varies continuously through the transition, a reasonable decomposition that accounts for a large percentage of the total noise is into conventional position and amplitude jitter of a fixed transition shape. The relative weights depend on the head-medium parameters; for current head-medium configurations and for longitudinal recording, position jitter dominates. A simple closed form expression for the noise power spectrum is given. Published experimental measurements of signal and noise spectra made with pseudo-random write data compare extremely well with this theoretical analysis, and lead to very good estimates for a and s. The analysis is general and applies for low-density recording with both inductive and magnetoresistive heads as well as all magnetization orientations.<
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